Sulfonation of poly-alkyl substituted aromatic hydrocarbons



United States Patent SULFONATION OF POLY-ALKYL SUBSTITUTED AROMATICHYDROCARBONS Joseph Edward Mitchell, East Rutherford, and Walter RussellTrent, North Arlington, N. 3., assignors to Colgate-Palmolive Company,Jersey City, N. J., a corporation of Delaware No Drawing. ApplicationNovember 23, 1949, Serial No. 129,194

7 Claims. (Cl. 260-505) This invention relates to the sulfonation ofhydrocarbons and more particularly to a process of sulfonatingpolysubstituted aromatic hydrocarbons in the production of alkylaromatic sulfonic acids or salts thereof having surface-activeproperties. The invention is especially useful in the sulfonation ofpolyalkyl-substituted aromatic hydrocarbon mixtures which areconveniently referred to hereinafter as alkylated homologues of benzene.Such compounds may be represented by the following general formulae andwherein R represents a straight or branched aliphatic chain containingfrom about 10 to 18 carbon atoms, R and R are short-chain alkyl radicalsof from 1 to 3 carbon atoms. Hydrocarbons of this class, or mixturesthereof, have been prepared heretofore, for example by suitablycondensing an olefin hydrocarbon fraction boiling between about 150 and275 C. with toluene or xylene, or the like homologue of benzene, toprovide a hydrocarbon mixture or alkane distilling within a range ofabout 250 to 400 C., the boiling temperature ranges being at ordinaryatmospheric pressure conditions, i. e. 760 mm. of mercury.

One method of preparing such alkylated aromatic compounds comprises thechlorination of a kerosene, or similar close-cut petroleum fraction e.g. boiling between 150 and 275 C., as described, and catalyticallycondensing the resultant chlorinated compound with an aromatichydrocarbon. The alkyl aromatic compound thus formed is then suitablysulfonated to produce a monosulfonated alkylated aromatic product, thesulfo group being attached to the aromatic ring. The watersolublesulfonates, as well as the alkali, alkali-metal or ammonium salts, ofthese alkylated aryl hydrocarbons or alkanes have distinctivesurface-active properties which make them suitable for use as detergentsand wetting and emulsifying agents.

Such alkyl aryl hydrocarbon mixtures heretofore, however, have beendifiicult to sulfonate to produce a product which is of good color andfree from objectionable odors, and having a high yield of alkyl arylsulfonate. Moreover, generally a large excess of the sulfonating agenthas been required to efiect sulfonation. Another difiiculty encounteredhas been that de-alkylation of the hydrocarbon takes place to anundesirable extent with the formation of lower sulfonated side-reactionproducts and unsulfonated residues. The presence of such lowers'ulfonatedreaction products and unsulfonate'd residues in thesulfonated product is highly undesirable because the detergency power isdecreased thereby. Further, such by-products tend to impart color and/orodor to the sulfonated mixture and give it a tackiness which lessens thecommercial value of the product particularly for detergent purposes. Theuse of large excesses of the sulfonating agent also is undesirableespecially where the resultant sulfonate mixture is to be neutralized toprovide a water-soluble salt having a high proportion of alkyl arylsulfonate salt.

The present invention provides an improved process of carrying out thesulfonation of such alkyl substituted aromatic hydrocarbon mixtures toobtain a yield of up wards of while employing a minimum quantity of thesulfonating agent. The method permits the sulfonation reaction to becarried out at fairly low temperatures and which are commerciallypracticable. Decomposition of the alkylated hydrocarbons duringsulfonation and the formation of detrimental side-reaction productsarelargely prevented whereby a sulfonated mixture is produced which islight in color and relatively free from objectionable odors andstickiness which heretofore have characterized such sulfonated mixtures.Further, employing the method of the invention there is produced asulfonic acid product which after neutralization gives a compositioncontaining about 50% by weight of sulfonated alkyl aryl material, whichis the active ingredient. By so doing, the inclusion of builders or thelike substances, for enhancing the'detergency properties such assoil-removing power, foaming and/or wetting characteristics of thedetergent is permitted without lowering the percentage content of theorganic sulfonate salt to such an extent that the efiiciency of theproduct is detrimentally alfected.

In accordance with the invention the sulfonation of these alkylatedhomologues of benzene may be accomplished with the production of a highyield of alkyl aryl sulfonic acid, for example between and by carryingout the sulfonation in the presence of a relatively large amount ofphosphorus pentoxide or suitable compound containing phosphoruspentoxide. Compounds which have been found particularly effective forthis purpose, when used in substantial amounts, for example such as toprovide at least about 5% by weight of P205 based on the weight ofalkylated aryl hydrocarbon mixture being sulfonated, are phosphoruspentoxide and phosphoric acid derivatives thereof, especiallytetraphosuhoric acid. Phosphorus pentoxide and the phosphoric acidderivatives are referred to in the annexed claims as phosphoruspentoxide catalyst and it will be understood that such terminologyconnotes both phosphorus oxide derivatives as well as phosphoruspentoxide.

The reason for the high sulfonation yield and improved quality of theproduct obtained by carrying out the sulfonation in the presence of acomparatively large amount of phosphorus pentoxide or oxygen-containingphosphorus compound providing an equivalent amount of P205, is notunderstood and appears to bear no particular relationship to the knowndehydrating properties of phosphorus pentoxide and as will be shown bycertain examples hereinafter described. The action of the phosphoruspentoxide compound apparently is more of a synergistic nature inasmuchas de-alkylation of the aromatic hydrocarbon or breaking-up of the longalkyl carbon-chain into fragments is substantially inhibited, while atthe same time a catalytic substitution-influencing effect is exertedwhich brings about the ready entry of the sulfo-group in the ringstructure to produce the desired monosulfo-aromatic compound. This dualfunction of the phosphorus compound manifests itself in the high yieldof organic sulfonate obtained and excellent color and relative freedomfrom odor of the sulfonated mixture. A further advantage attained by theuse of phosphoric pentoxide or phosphoric pentoxide-containing compoundis that where the resultant sulfonate mixture is neutralized with alkalito form water-soluble salts thereof a certain amount of alkali phosphateis formed in situ. Such by-product phosphates partic ularly alkali metalphosphates viz. sodium tetraphosphate, trisodium phosphate, sodiumpolyphosphate, etc., are known water conditioners and are generallyincorporated in varying amounts to provide improved detergencycharacteristics. Utilizing the process of the invention to prepare analkylated aryl sulfonate detergent, the subsequent addition of alkalimetal phosphates and the like inorganic builders is made unnecessary,being formed in situ during neutralization of the sulfonated mixture.

In the following table there is shown the results of a number ofsulfonation runs made using alkylated toluene-type petroleum fractionssupplied by different refineries and having a boiling range atatmospheric pressure between about 250 and 400 C. (50% boiling over 300C.); and having a specific gravity of 20 C. of approximately 0.87 and aflash point in open cup of about 175 C. Fuming sulfuric acid containing20% S: was employed as the sulfonating agent, and the ratio by weight ofhydrocarbons to sulfonating agent in each case was approximately 1:1.The sulfonating reaction was initiated at a temperature between 0 and C.followed by the aging time and temperature shown. The control representsthe average yield obtained using alkylated toluene hydrocarbon fractionsas supplied by four different refineries and boiling .between 250 and400 C. as aforementioned. The percentage proportion of catalyst used isbased on the weight of the hydrocarbon mixture being sulfonated.

' Approximately 85% P105.

As the tabulated results indicate, where upwards of 5% phosphoruspentoxide is present, based on the weight of hydrocarbon beingsulfonated, the sulfonation yield is on the order of 90% or better. Thishigh yield is obtained employing only a 1:1 weight ratio of hydrocarbonto fuming sulfuric acid. In the runs made utilizing tetraphosphoric acidlarger proportionate amounts of the phosphoric acid were required inorder to obtain yields of 90% or more. This is believed to be due to thefact that only part of the P205 is released or otherwise made availableduring the sulfonation reaction to perform the desired catalytic action.

In order to compare the effect produced with phosphorus oxide catalystswith that obtained when a like amount of a different dehydrating agentis employed, additional tests were made using by weight boron trioxidein place of phosphorus pentoxide. Sulfonation test runs made with borontrioxide under the same conditions as described in the above table andusing 1:1 weight ratio of alkylated toluene hydrocarbon to fumingsulfuric acid gave a sulfonation yield of 63.0% on a batch sulfonatedand aged at C. for one-half of an hour, and a 69.0% yield on a likebatch aged at C. for the same period. The results thus obtained withboron trioxide indicate that the improved results produced withphosphorus pentoxide or phosphorus pentoxide-containing compounds arenot primarily dependent, at least, on the dehydrating characteristicproperty of the compound. Further, while it has been proposed in theliterature to use oxygen-containing phosphorus compounds as dehydratingagents in sulfonation processes generally, it has not been knownheretofore that the sulfonation of alkylated homologues of benzene couldbe markedly improved with respect to the quality and yield of theorganic sulfonate product produced by sulfonating in the presence of asufiicient amount of phosphorus pentoxide. The improvement is achievedemploying a minimum amount of sulfonating agent by carrying out thesulfonation reaction in the presence of a relatively large proportionateamount of phosphorus pentoxide or phosphorus compound containingphosphorus pentoxide.

Additional sulfonation test runs which were carried out using in onecase alkylated benzene, for example, dodecyl benzene and in another analkylated benzene homologue,

Table 2 Average Percent Hydrocarbon Catalyst, Percent Yield OrganicSulfonate Dodecyl benzene. None 95 Dodecyl toluene.-. .do Do P105 (10%by wt. of hydrocarbon) 95 As the data of Table 2 indicates, there is noparticular difiiculty in obtaining sulfonation yields of over with thealkylated benzene-type hydrocarbons. On the other hand wherepoly-substituted benzene compounds, such as alkylated toluene, is usedthe yield is poor unless sufiicient phosphorus pentoxide is presentduring sulfonation. Using less than about 5% by weight phosphoruspentoxide, based on the weight of the hydrocarbon present however,produces yields below 90% which is usually undesired. Moreover, it hasbeen observed that where the sulfonation of the alkylated homologues ofbenzene is carried out omitting the catalyst but employing largerproportionate amounts by weight of sulfuric acid, for example on theorder of 1.5 to 2 parts sulfuric acid to one part hydrocarbon, the yieldis increased but the sulfonated mixture is somewhat darker in color andof inferior quality as compared with the same product made using lesssulfonating agent, and which sulfonation reaction is carried out in thepresence of phosphorus pentoxide as described. Moreover, the use oflarger than 1:1 weight proportions of hydrocarbon to sulfonating agent,as heretofore mentioned, provides a product after neutralization withalkali which contains a high proportionate amount of inorganic sulfateand a correspondingly lower percentage of organic sulfonate or activeingredient. Accordingly, where it is desired to provide a finishedsulfonated product having a high proportion of active ingredient it isimperative that the excess of sulfuric acid, over that required tosubstantially completely sulfonate by hydrocarbon present, he kept to aminimum otherwise upon neutralization of the sulfonated mixture, thepercentage amount of organic sulfonate present will be correspondinglydecreased due to the increased amount of inorganic sulfate formed.

The invention is further illustrated by the following examples but itwill be understood that the same is not limited thereto.

Example I To 200 grams of aryl alkylate (principally dodecyl toluene)having a specific gravity of 0.371 at 20C. and boiling between about 290and 330 C. (50% boiling over 300 C.) is added 40 grams oftetraphosphoric acid. The resultant mixture is placed in a round bottomflask equipped with a thermometer and mechanical stirrer, the flaskbeing cooled by a methanol and Dry Ice bath, and while the temperatureis kept at about 0 to 10 C., 203 grams of fuming sulfuric acid (20% S03)is added slowly while the mixture is stirred vigorously. After all thesulfuric acid is added the cooling bath is replaced with a warm waterbath and the mixture is divided into two portions one of which is agedthirty minutes at 30 C. and the other for half an hour at 50 C. Theyield of organic sulfonate at both 30 C. and 50 C. is approximatelyExample 2 A portion of the aryl aromatic sulfonate prepared as describedin Example 1 is neutralized with sodium hy' droxide and roll-dried toproduce a detergent composition containing about 50% active ingredientand 11.14% sodium phosphate, the remainder being principally sodiumsulfate. The product is of light color and is substantially' free ofodor,

forming an excellent wetting and detersive agent.

Example 3 i Two hundredgrams' of aryl alkylate as described Example 1-is reacted with 203 grams of fuming sulfuric acid (20% $03) in thepresence' of 30' grams of P205. The yield of. aliquots sulfonated andaged. at both 30 and 50 C'. is approximately 96% of the theoretical.

Example 4 Example 5 A sulfonation run is carried out as described inExample 1 using 100 parts of aryl alkylate distillate but supplied froma difierent source. One hundred grams of the hydrocarbon is reacted at 0to C. with 10l.5= grams of fuming sulfuric S03), and using 40 grams oftetraphosphoric acid as the catalyst. The organic sulfonate yield uponaddition of the oleum and aging at 50 C. for one-half hour is found tobe 95% in this instance.

Example 6 Upon roll-drying a sample portion of the sulfonate mixtureprepared as described in Example 5, which is neutralized with sodiumhydroxide, a superior detergent product is provided which containsapproximately 51.00% active ingredient and 14.22% sodium phosphate whichis formed in situ during neutralization of the sulfonate mixture.

Instead of roll-drying the neutralized sulfonate mixtures as described,the salt mixture may be spray-dried to form a solid detergent product.

While in the above examples the sulfonating agent used is fumingsulfuric or oleum, other suitable sulfonating agents may be utilized forthis purpose, for example 100% sulfuric acid, sulfur trioxide, etc.Similarly, the hydrocarbon material may comprise alkylated toluene orxylene compounds, such as the monoary -substituted polymers viz.propylene polymers in which the aryl substituent is a mono-nuclearhydrocarbon of toluene, xylene or the like homologue of benzene, thepolymer portion being of relatively high molecular weight but preferablyboiling below about 300 C. Mixtures of these hydrocarbon polymers withcorresponding benzene substituted hydrocarbons are also applicable forsulfonation in accordance with the present invention.

Although the sulfonation process is preferably carried out using a 1:1ratio by weight of alkyl aryl hydrocarbon mixture and sulfonating agent,improved results as regards yield and quality of product may be attainedusing slightly higher or lower proportionate amounts of the ingredients.Also where it is desired, the phosphoric acid catalyst may be introducedinto the oleum prior to mixing the same with the hydrocarbon to besulfonated or the catalyst may be introduced concurrently duringaddition of the sulfonating agent. The sulfonation reaction may also becarried out at higher temperatures, for example at ordinary roomtemperatures or above, but it is preferred that the temperature be keptbelow about C to obtain the best results.

The process of the invention provides an improved method of sulfonatingpoly-substituted aromatic compounds, viz. alkylated toluene, xylene,etc., which heretofore have been difiicult to sulfonate and produce asatisfactory product of good quality, high yield and which issubstantially free of odor and color bodies and unsulfonated residues.The present method makes it possible to produce superior syntheticdetergent compositions of the alkyl aryl sulfonate type which comprisesupwards of 50% by weight of alkyl aryl sulfonate salt or activeingredient without the necessity and expense of concentrating the alkylaromatic sulfonic acids produced during sulfonation. Upon neutralizationof the sulfonated mixture, moreover, there is produced a water-solublesalt detergent composition containing not only a high percentage amountof active ingredient but a desirable amount of alkali phosphate whichisformed in situ, the proportion of. active ingredient and phosphatesalt in the mixture being on the order of 50 to 60% and 10 to 20% byweight respectively. This is in marked contrast to theordinaryproduction of such synthetic detergent compositions wherein theactive ingredient in the neutralized mass is on the order of 35 to 40%by weight of the mixture and alkali phosphate builders, where desired,must be suitably admixed therewith. In addition, the invention providesfor the utilization of less costly hydrocarbons in the production ofalkyl aryl detergents, wetting agents and surface-active compositions.It is also possible to su lfonate alkylated homologues of benzene so asto obtain a yield of or better, while using less proportionate amountsof the sulfonating agent than has been considered practicable heretoforein the commercial production of such aryl aromatic sulfonates.

It will be understood that various modifications and substitutions maybe utilized for carrying out the process and such as will occur to thoseskilled in the art. Such modifications and variations are intended to becovered by the present invention, the same being limited only by theexpressed limitations in the appended claims.

What is claimed is: V

I. An' improved process for sulfonating polyalkylated aromatichydrocarbons which consists in reacting a sulfonating agent with ahydrocarbon mixture which distills between about 250 and about 400 C.and which contains principally alkylated benzene homologues of the typerepresented by the general formula wherein R represents an alkyl radicalwhich has a carbon chain corresponding to that contained in an olefinboiling between about and about 275 C., R is a short chain alkyl radicalof l to 3 carbon atoms, and R" is a material selected from the groupconsisting of hydrogen and an alkyl radical of l to 3 carbon atoms, saidsulfonation reaction being carried out in the presence of a catalystselected from the group consisting of phosphorous pentoxide andphosphoric acid derivatives thereof, said sulfonation reaction beingcarried out in the presence of only the recited materials and saidcatalyst being present in an amount approximating at least 5% by weightof phosphorous pentoxide based on the weight of said hydrocarbonmixture.

2. A process as set forth in claim I in which the sulfonating agentcomprises fuming sulfuric acid.

An improved process for the monosulfonation of polyalkylated aromatichydrocarbons comprising principally alkyl substituted homologues ofbenzene of the type represented by the general formula and saidphosphorous pentoxide being present in an amount approximating at least5% hydrocarbon mixture.

4. An improved process for the monosulfonation of polyalkylated aromatichydrocarbons comprising principally alkyl substituted homologues ofbenzene of the type represented by the general formula by weight of saidwherein R represents an aliphatic chain of 10 to 18 carbon atoms, R is ashort chain alkyl radical of, 1 to 3 carbon atoms, and R" is a materialselected from the group consisting of hydrogen and an alkyl radical of lto 3 carbon atoms, which consists in mixing and reacting saidhydrocarbon mixture with a sulfonating agent in the presence of aphosphoric acid derivative of phosphorous pentoxide, said sulfonationreaction being carried out in the presence of only the recited materialsand said phosphoric acid derivative being present in an amountapproximating at least 5% by weight of phosphorous pentoxide based onthe weight of said hydrocarbon mixture.

5. A process as set forth in claim 4 in which said phosphoric acidderivative of phosphorous pentoxide is tetraphosphoric acid.

6. An improved process for sulfonating a hydrocarbon mixture comprisingan alkyl substituted toluene wherein the alkyl substituent containsabout to about 18 carbon atoms and has a boiling point within the rangeof about 150 to about 275 C., which consists in mixing and reacting saidhydrocarbon mixture with sulfuric acid in the presence of a catalystselected from the group consisting of phosphorous pentoxide andphosphoric acid derivatives thereof, said sulfonation reaction beingcarried out m the presence of only the recited materials and saidcatalyst being present in an amount equivalent to at least about 5% byweight of phosphorous pentoxide based on the weight of the hydrocarbonmixture being sulfonated.

7. A process for the production of alkyl aryl sulfonate detergent saltswhich consists in reacting a sulfonating agent with a hydrocarbonmixture consisting essentially of monoalkylated toluencs obtained byalkylating toluene with an aliphatic hydrocarbon fraction distillingwithin the range of about to about 275 C., said reaction being carriedout in the presence of a catalyst selected from the group consisting ofphosphorous pentoxide and phosphoric acid derivatives thereof, saidsulfonation reaction being carried out in the presence of only therecited materials and said catalyst being present in an amountapproximating at least 5% by weight of phosphorous pentoxide based onthe weight of said hydrocarbon mixture, and neutralizing the resultantmixture.

References Cited in the file of this patent UNITED STATES PATENTS NumberRe. 22,548 2,223 ,364

1. AN IMPROVED PROCESS FOR SULFONATING POLYALKYLATED AROMATICHYDROCARBONS WHICH CONSISTS IN REACTING A SULFONATING AGENT WITH AHYDROCARBON MIXTURE WHICH DISTILLS BETWEEN ABOUT 250* AND ABOUT 400* C.AND WHICH CONTAINS PRINCIPALLY ALKYLATED BENZENE HOMOLOGUES OF THE TYPEREPRESENTED BY THE GENERAL FORMULA